- 1 Definition/Description
- 2 Clinically Relevant Anatomy
- 3 Epidemiology /Etiology
- 4 Characteristics/Clinical Presentation
- 5 Differential Diagnosis
- 6 Diagnostic Procedures
- 7 Outcome Measures
- 8 Examination
- 9 Medical Management
- 10 Physical Therapy Management
- 11 Example management programmes
- 12 References
Clinical instability of the cervical spine is defined as the inability of the spine under physiological loads to maintain its normal pattern of displacement so that there is no neurological damage or irritation, no development of deformity, and no incapacitating pain. While no tools exists for the assessment of upper cervical ligamentous instability, an approach that takes into account risk factors, patient history, and examination results to make judicious decisions about patient management has been recommended.
Clinically Relevant Anatomy
The cervical spine consist of 7 separate vertebrae. The first two vertebrae (referred as upper cervical spine) are highly specialised and differ from the other 5 cervical vertebrae (lower cervical) regarding anatomical structure and function.
The upper cervical spine is made of the atlas (C1) and the axis (C2). It comprises of two joint structures: one in between os occipital and atlas (atlanto-occipital joint), the other one between atlas and axis, which forms the atlanto-axial joint. The atlantoaxial joint is responsible for 60% of all cervical rotation; the atlanto-occipital joint is responsible for 33% of flexion and extension. 
The craniocervical junction (atlanto-occipital joint), the lower atlanto-axial joint and other cervical segments are reinforced by internal as well as external ligaments. They secure the spinal stability of the cervical spine as a whole, together with surrounding postural muscles and allow cervical motion. They also provide proprioceptive information throughout the spinal nerve system to the brain.
The cervical spine has sacrificed stability for mobility and is therefore vulnerable to injury. The orientation of the cervical spine facet joints means the cervical spine is designed for a great deal of mobility, but it lacks stability. The nonlinear displacement curve of the spine, the total range of motion of a spinal segment may be divided into the neutral zone and the elastic zone:
- Neutral zone: motion occurring in this zone is produced against a minimal passive resistance.
- Elastic zone: motion occurring in occurring near the end-range of spinal motion is produced against increased passive resistance.
There are many authors that identified common components of spinal stability. Panjabi conceptualised the components into 3 functionally integrated subsystems of the spinal stabilising system:
The passive subsystem:
- Consists of vertebral bodies, facet joints and capsules, spinal ligaments (lig. longitudinale anterius and posterius, ligamentum interspinosum, lig. Interspinosus and lig. Flavum).
- Passive tension from spinal muscles and tendons.
- Provides significant stabilization of the elastic zone and limits the size of the neutral zone.
- Acts as a transducer and provides the neural control subsystem with information about vertebral position and motion
The active subsystem:
- Consists of spinal muscles and tendons, such as: multifidus cervicis, Longus capitis and the Longus Colli.
- Generates forces required to stabilize the spine in response to changing loads.
- Controls the motion occurring within the neutral zone and contributes to maintain the size the size of the neutral zone.
- Acts also as a transducer by providing the neural control subsystem with information about the forces generated by each muscle.
The neural control subsystem:
- Consists of peripheral nerves and the central nervous system.
- Receives information from the transducers of the passive and active subsystems about vertebral position, vertebral motion, and forces generated by spinal muscles. The subsystem determines the requirements for spinal stability and acts on the spinal muscles to produce the required forces.
Clinical instability of the spine occurs when the neutral zone increases relative to the total ROM, the stabilizing subsystems are unable to compensate for this increase, which causes a poor and uncontrolled quality of motion in the neutral zone.  Degeneration and mechanical injury of the spinal stabilisation components are the primary causes of increases in neutral zone size.
It is generally accepted that cervical instability is caused by trauma (one major trauma or repetitive microtrauma). Cervical instability can also be a cause of delayed or missed diagnosis of cervical spine injury occurred after trauma (car accident, high impact on the neck) . The traumatic flexion-extension moment exerted on the spine can cause ligamentous disruption with subsequent atlantoaxial instability (AAI) also known as upper cervical instability. Although this occurs in very rare case its incidence is between 4.9 to 20%.
Cervical instability is often diagnosed in patients with rheumatoid arthritis, due to the progressive destruction of the cervical skeletal structures. The most affected region is the upper cervical spine and C4-C5. 
Congenital deviation (eg, down syndrome) also can cause upper cervical spine instability. The atlanto-axial instability (AAI) is considered as a developmental anomaly often occurring in patient with the down’s syndrome (DS). It affects 6.8 to 27% of the population with DS. Usually, persons with congenital anomalies do not become symptomatic before midlife adulthood. The spine is assumed to be able to accommodate differing regions of hypermobility and fusions. With time, the degenerative changes occurring in the lower cervical spine increase rigidity and alter the balance. This gradual loss of motion places increasing loads on the atlantoaxial articulation
The following risk factors are associated with the potential for bony or ligamentous compromise of the upper cervical spine:
- History of trauma (e.g. whiplash, rugby neck injury)
- Throat infection
- Congenital collagenous compromise (e.g. syndromes: Down’s, Ehlers-Danlos, Grisel, Morquio)
- Inflammatory arthritides (e.g. rheumatoid arthritis, ankylosing spondylitis)
- Recent neck/head/dental surgery.
There is a large agreement on following symptoms to make a clinical judgment on CCSI: “intolerance to prolonged static postures,” “fatigue and inability to hold head up,” “better with external support, including hands or collar,” “frequent need for self-manipulation,” “feeling of instability, shaking, or lack of control,” “frequent episodes of acute attacks,” and “sharp pain, possibly with sudden movements.”
The physical examination findings related to cervical instability that reached the highest consensus among specialists included “poor coordination/neuromuscular control, including poor recruitment and dissociation of cervical segments with movement,” “abnormal joint play,” “motion that is not smooth throughout range (of motion), including segmental hinging, pivoting, or fulcruming,” and “aberrant movement.” Aberrant motions occurring in the mid-ranges of active cervical movement are cardinal signs of cervical clinical instability
Symptoms can be different but the most frequent clinical findings are:
- Tenderness in the cervical region
- Referred pain in the shoulder or paraspinal region
- Cervical radiculopathy
- Cervical myelopathy
- Paraspinal muscle spasm
- Decreased cervical lordosis
- Neck pain with sustained postures
- Hypermobility and soft end-feeling in passive motion testing
- Poor cervical muscle strength (multifidus, longus capitis, longus colli)
It’s important to remember that problems in de neck region can be masked by problems in other regions of the body. A frozen shoulder (adhesive capsulitis) for example can be seen in conjunction with a cervical radiculopathy. Other shoulder pathologies such as brachial plexitis can also cause pain and weakness of muscles in the shoulder-neck-region. [LOE 5].
Certain Patients that might present acute neurologic symptoms that raise alarm for cervical compression or neck pain but without a specific origin should undergo a thorough physical examination and radiographic evaluation to determine the source.
More often than not are the findings nonspecific and can be representative of any number of related conditions. Neck pain, weakness and other characteristics also present in cervical spine instability can also be seen in the following cervical diseases including the following: 
- Cervical strain
- Cervical trauma or fracture
- Occipital headaches
- Degenerative disease of the spine
- Previously undiagnosed syndrome
- Neurological involvement
- Progressive neck pain
- Resistant neck pain
- Central or lateral disc herniation
- Guillain-Barré syndrome
- Cervical spondylosis
- Pathologic fracture
- Cervical canal stenosis
- Facet joint pathologies
- Infections: discitis, osteomyelitis, etc.
Cervical instability is a diagnosis based primarily on a patient’s history and reported symptoms.
Objective criteria have been established in the analysis of end-range flexion and extension radiographs to diagnose cervical spine instability. However, radiographs do not provide information about the quantity or quality of motion in the neutral zone (ie, mid-range), which limits their value in the diagnosis of cervical spine clinical instability.
There is often little correlation between the degree of instability or hypermobility shown on radiographic studies and clinical symptoms. Even after severe whiplash injuries, plain radiographs are usually normal despite clinical findings indicating the presence of soft tissue damage. 
MRI images could be useful to screen the integrity of the vertebral ligaments. Taking images during an anterior shear test or a distraction test shows a greater intervertebral distance and an increase in direct length of the ligaments.
However, functional computerized tomography (fCT) and magnetic resonance imaging (fMRI) scans and digital motion x-ray (DMX) are able to adequately depict cervical instability pathology . Studies using fCT for diagnosing soft tissue ligament or post-whiplash injuries have demonstrated the ability of this technique to show excess atlanto-occipital or atlanto-axial movement during axial rotation . This is especially pertinent when patients have signs and symptoms of cervical instability, yet have normal MRIs in a neutral position.
Functional imaging technology, as opposed to static standard films, is necessary for adequate radiologic depiction of instability in the cervical spine because they provide dynamic imaging (flexion and extension images of the spine) of the neck during movement and are helpful for evaluating the presence and degree of cervical instability. (LOE 2B)
Cook et al tired to obtain consensus of symptoms and physical examination findings associated with clinical cervical spine instability. The study resulted in a list of 16 symptoms and 12 physical examination findings that is associated with CCSI.
The related symptoms listed in descending rank of relationship are:
- Intolerance to prolonged static postures
- Fatigue and inability to hold head up
- Better with external support, including hands or collar
- Frequent need for self-manipulation
- Feeling of instability, shaking, or lack of control
- Frequent episodes of acute attacks
- Sharp pain, possibly with sudden movements
- Head feels heavy
- Neck gets stuck, or locks, with movement
- Better in unloaded position such as lying down
- Catching, clicking, clunking, and popping sensation
- Past history of neck dysfunction or trauma
- Trivial movements provoke symptoms
- Muscles feel tight or stiff
- Unwillingness, apprehension, or fear of movement
- Temporary improvement with clinical manipulation
The 12 physical examination findings included:
- Poor coordination/neuromuscular control, including poor recruitment and dissociation of cervical segments with movemen
- Abnormal joint play
- Motion that is not smooth throughout range (of motion), including segmental hinging, pivoting, or fulcruming
- Aberrant movement
- Hypomobility of upper thoracic spine
- Increased muscle guarding, tone, or spasms with test movements
- Palpable instability during test movements
- Jerkiness or juddering of motion during cervical movement
- Decreased cervical muscle strength
- Catching, clicking, clunking, popping sensation heard during movement assessment
- Fear, apprehension, or decreased willingness to move during examination
- Pain provocation with joint-play testing
To measure chronic neck pain we can use the neck disability index, the neck bournemouth questionnaire or the neck pain and disability scale. These three questionnaires are specific and valid instruments to evaluate the neckpain and dysfunction. 
The pain catastrophizing scale can be used to evaluate how the patient experiences the pain. It measures the rumination, magnification and helplessness of the patient. 
Because a definitive diagnostic tool has not been developed, cervical clinical instability will continue to be diagnosed through clinical findings, including history, subjective complaints, visual analysis of active motion quality, and manual examination methods.
Cook et al proposed different identifiers for cervical spine instability. They divided them into different categories: movements, descriptive components, and postures. Patients also experienced neurological problems and headaches.
- The neck locks when doing certain movements
- A sharp pain can be provoked by certain movements
- Banal movements provoke symptoms out of proportion
- Patients are not willing to move their neck into areas beyond their comfort zone
- History of a trauma or neckdysfunction(cervicogenic headaches, chronic whiplash dysfunction, rheumatoid arthritis, osteoarthritis, and segmental degeneration)
- Supporting the neck with a brace or hands causes relief of symptoms
The neck feels instable
- Catching or clicking sensation when moving the neck
- The musculature of the neck feels stiff
- The pain is worse at the end of the day
- Neck pain or headaches provoked by static weight bearing postures
- Relieved by non-weightbearing postures
The following tests can be used to measure cervical instability but little is known about the diagnostic accuracy of upper cervical spine instability tests:
- Sharp-Purser test
- Transverse Ligament Stress Test
- Cervical flexion-rotation test
- Neck Flexor Muscle Endurance Test and Craniocervical flexion test
One high quality systematic review by Hutting et al revealed poor diagnostic accuracy for all upper cervical ligament instability tests evaluated. In general, these tests have sufficient specificity and can rule in upper cervical ligamentous instability, but degrees of sensitivity varied.
Magee et al reported poor cervical muscle endurance is one of the clinical findings we find with cervical instability. A good way to test these muscles (the deep cervical flexor muscles, the longus capitis and longus colli) is the craniocervical flexion test (CCFT) which is a test of neuromotor control. The main goal of the test is to aply an isometric force on a pressure sensor placed behind the neck without using the superficial cervical flexors. The construct validity of the craniocervical flexiontest has ben verified in a laboratory setting
In the past few decades nonoperative maneuvers like traction, cast immobilization and long periods of bed rest had been replaced by the use of instrumentation to stabilize the spine after a trauma. This method can reduce the risk of negative sequelae of long term bed rest. The cervical stability can be received by using posterior fixation such as lateral mass plating, processus spinosus or facet wiring and cervical pedicle screws. The choice of which fixation is best, can be made by the surgeon after seeing a CT-scan or MRI. In a retrospective study of Fehlings, the cervical spine stabilisation was successful in 93% off the cases. Obviously this fixation procedure also holds some risks. It is possible that the spinal cord, vertebral artery, spinal nerve and facet joints get injured.
Physical Therapy Management
Conservative treatment is indicated when cervical clinical instability does not severely involve or threaten neurological structures. The goal of nonsurgical treatment should be to enhance the function of the spinal stabilising subsystems and to decrease the stresses on the involved spinal segments.
Posture education and spinal manipulation
- Decreases stresses on the passive subsystem
- Proper posture: reduces the loads placed on the spinal segments at end-ranges and returns the spine to a biomechanically efficient position
- Spinal manipulation can be performed on hypomobile segments above and below the level of instability, what eventually will result in a distribution of the spinal movement across several segments. Also the mechanical stresses on the level of clinical instability are believed to be decreased
- Video over joint mobilisation: https://www.youtube.com/watch?v=Rn1Ed2SxTx0
- Enhances the function of the active subsystem.
- The cervical multifidus may provide stability via segmental attachments to cervical vertebrae.
- The longus colli and capitus provide anterior stability.
- Strengthening the stabilizing muscles may enable those muscles to improve the quality and control of movement occurring within the neutral zone.
- Exercise video: Neck strength and stability www.youtube.com/watch
One of the main goals of the non-surgical treatment is to improve the quality of controlled motion. Therefore proprioception exercises must be used, this will improve the control of movement in the neutral zone.
In a more specific situation such as post-operative rehabilitation the treatment can differ:
- The patient is not required to wear a brace.
- After 6 weeks it is not encouraged to do any lifting more than 4kg as also overhead work.
- The rehabilitation begins at week 6, mostly a basic stability exercises program.
- No cervical strengthening or ranges of motion exercises are encouraged in the first 6 months.
- The exercises or mainly focused on the neutral postural alignment, were the patients are recommended to us there trunk, hips and chest to produce proper cervical alignment.
Example management programmes
Therapeutic manipulations (mostely for headache)
- Second rib manipulation using supine thrust technique
- Upper thoracic manipulation (high-velocity thrust)
- Cervical facet joint upglide manipulation (grade IV)
- Suboccipital distraction with C2 stabilization
- Upper thoracic rotation manipulation (grade III)
Active exercise therapy
- Partial suboccipital nod with a head lift in supine to strengthen the longus capitus and longus colli muscles - The patient lies on his back with his head on the table/a pillow. He nods and hold this position as he lift his head off the table/pillow. This position is hold during 2-3 seconds and then the patient lowers his head back on the table/pillow. 3-4 sets of 10 repetitions were performed.
- Active suboccipital nodding - The patient lies on his back with a pillow under his head and nods. The physiotherapist applies a little resistance to prevent the patient to perform a neck flexion. The patient is then asked to bend his neck from a neutral position to the point of first resistance and then return to a neutral position. The patient is instructed to keep her head on the pillow throughout performance of the exercise. 3-4 sets of 10 repetitions were performed.
- Craniovertebral sidebending isometric manipulation - With the patient in supine, head resting on a low pillow, passively position the cran- iovertebral region into right sidebending to the point of resistance to the motion. Manually resist further right sidebending by applying manual pressure above the right ear as the patient holds isometrically for 10 seconds. Passively reposition the patient into further right sidebending if the passive motion has improved, and then reapply the isometric force for 10 seconds. This sequence is repeated 3-4 times in 1 session.
- Quadruped position arm lift with spinal stabilisation.
All those exercises can be performed at home in 3-4 sets of 10 repetitions.
Gros et al
Anita R. Gross et al listed an evidence-based home neck care exercise program that can be included if the CCFT test was found positive. It is in 3 progressive phases. These exercises should be judiciously tailored to individual circumstances and applied as indicated based on a clinical examination
- Craniocervical flexion- Start with pressure biofeedback inflated to 20 mmHg. Make sure your chin and forehead are lined up. Nod your head, keeping the large neck muscles soft and bringing the reading up to 22 mmHg. Work up to ten 10-second holds. Then progress to 24, 26, and 28 mmHg.
- Neck active range of motion - Start with your head in neutral, then:
- Tilt backward
- Bend forward
- Tilt side to side
- Turn side to side
- Resisted shoulder extension with elbow flexed - “Set” your cervical spine, abdominals and scapulae, then extend your arm with elbows bent backward.
- Resisted shoulder extension with elbow straight - “Set” your cervical spine, abdominals, and scapulae, then extend your arm backward.
- Resisted shoulder shrug -“Set” your cervical spine, abdominals, and scapulae, then slightly abduct arms and minimally shrug shoulders.
- Resisted elbow exercise - “Set” your cervical spine, abdominals, and scapulae, then:
- Straighten level 1
- Straighten level 2 your elbows.
- Headlift - Start with your head in neutral (chin and forehead lined up), do a chin nod and lift your head, while maintaining your chin tucked. Hold for a count of 5 to 10 seconds and return smoothly with your chin still tucked.
- Isometric neck strength - Place your hand on your head and resist. Hold for a count of 5 to 10 seconds:
- Tilting backward
- Tilting sideways
- Turning your head
- Shoulder stretches - “Set” your cervical spine, abdominals, and scapulae hold for 20 seconds.
- Clasp your hands behind your back and squeeze your scapulae together
- Hold your arms out in front of you and reach forward feeling a stretch between your scapulae
- Reach your arms overhead
- Shoulder stretches - “Set” your cervical spine, abdominals, and scapulae, hold for 20 seconds.
- With elbows at shoulder level, lean into a corner to feel a stretch in the front of your chest
- With elbows at eye level lean into a corner to feel a stretch
- Transverse abdominus - Tense your lower abdomen by imagining drawing your hip bones together (or apart if that works better), hold for 10 seconds. Then let the 1 leg fall out over a 10-second count
- Wall sit - “Set” cervical spine, transverse abdominus, and scapulae, then slide down the wall into a semi-squat position. Hold for as long as you can, working up to 2 minutes.
- Shoulder strength - “Set” cervical spine, abdominals, and scapulae then “hug a tree.”
- Shoulder strengthen - “Set” cervical spine, abdominals, and scapulae, then elevate arms into a “reverse fly.”
- Resisted neck: craniocervical flexion and oblique flexion - “Set” cervical spine, abdominals, and scapulae, then
- Nod head
- Nod head at a slight oblique angle
- Resisted neck extension - “Set” cervical spine, abdominals, and scapulae:
- First nod your head
- Then tilt your head backward
- The focus of extension is in the lower neck
- Resisted neck side flexion - “Set” cervical spine, abdominals, and scapulae, then tilt head to the side.
- Resisted neck rotation - “Set” cervical spine, transverse abdominus, and scapulae, then rotate head.
In the table below you can find the dosage recommendations for the evidence-based home neck care exercise program.
|Exercise||Equipment used||Load (pain-free or low pain)||Rep||Set||Frequency||Duration|
| Specific neck
Head weight/self resist
3 levels mmHg
| Postural/upper extremity
Specific neck 5
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